Wellbore system have been devised for multi-lateral wellbores which include a main wellbore extending from surface into the earth formation and one or more branch boreholes extending laterally from the main borehole. Such multi-lateral wells have great potential for increased productivity and reservoir access per well as the number of wells in an oil/gas field development is significantly reduced. However drilling time on a multi-lateral well can be considerably increased compared to a conventional well, thus potentially significantly delaying first oil/gas production.
It is an object of the invention to provide an improved wellbore system which overcomes the afore-mentioned problem, and which enables to reduce the time until first oil/gas production.